Influência do tipo de agente de partição da borracha nitrílica na obtenção de blendas PVC/NBR

Abstract

Resumo: Borrachas nitrílicas para utilização em misturas com PVC são fornecidas em forma de pó, que são recobertas com um agente de partição para evitar compactação do produto no transporte e armazenamento, além de garantir alta fluidez e livre escoamento. Neste trabalho, buscou-se estudar a influência do tipo de agente de partição da borracha nitrílica (resina de PVC e CaCO 3 ) na obtenção de blendas PVC/NBR. As propriedades mecânicas das blendas foram avaliadas por ensaios de tração, rasgo e dureza. As blendas com NBR com agente de partição de PVC apresentaram maior tensão na ruptura e módulo elástico que as blendas em que utilizaram NBR com agente de partição de CaCO 3 . A morfologia foi avaliada por microscopia eletrônica de varredura sendo bastante afetada pelo tipo de agente de partição. Palavras-chave: Blenda PVC/NBR, poli(cloreto de vinila), borracha nitrílica, agente de partição. Influence of the Partitioning Agent on the Preparation of PVC/NBR BlendsAbstract: Nitrile rubbers used in mixture with PVC resin are supplied in powder. This kind of nitrile rubber has a partitioning agent to avoid agglomeration in the particles during the transport and storage. In this study, the influence of the partitioning agent on the preparation of PVC/NBR blends was investigated. The mechanical properties of the blends were evaluated by tensile properties, tear strength and hardness. The PVC/NBR blends with partitioning agent of PVC showed an increase in the tensile stress and Young's modulus compared to the PVC/NBR blends with partitioning agent of CaCO 3 . The morphology of the blends examined by scanning electron microscopy demonstrated the influence of the partitioning agent.

Investigation of the phase morphology of dynamically vulcanized PVC/NBR blends using atomic force microscopy

“…Polymer blends have been employed to find new miscible combinations, since miscibility is a crucial factor in the development of the morphology of polymer blends 1, 2. To optimize processing and properties, it is important to know the polymer's melt rheology and the morphology of the resulting blend 1–3…”

“…Thus these properties of a nitrile rubber will be upgraded by modification with PVC 6. Among the many different procedures to prepare PVC/NBR blends, the dynamic vulcanization of elastomer during its mixture in the molten state with a thermoplastic has been studied by many authors 3–10. These systems have two main advantages over conventional systems, yielding vulcanized systems with reduced reversion and better aging characteristics.…”

“…Dynamic vulcanization is a process whereby a thermoplastic and an elastomer are mixed in the melt state, with simultaneous crosslinking of the elastomer 3, 11, 12. The quantity and type of crosslinking between the elastomeric chains formed during processing depend on the curative system used.…”